According to the Center for Disease Control (CDC), the prevalence of overweight and obesity has increased sharply for both adults and children over the past 30 years. Between 1976-1980 and 2003-2004, the prevalence of obesity among adults aged 20-74 years increased from 15.0% to 32.9%. Among young people, the prevalence of overweight increased from 5.0% to 13.9% for those aged 2-5 years, 6.5% to 18.8% for those aged 6-11 years, and 5.0% to 17.4% for those aged 12-19 years. Overweight and obesity ranges are determined by using weight and height to calculate a number called the “body mass index” (BMI). BMI is used because, for most people, it correlates with their amount of body fat. An adult who has a BMI between 25 and 29.9 is considered overweight, while an adult who has a BMI of 30 or higher is considered obese. Within the obesity category, a person is morbidly obese if he meets one of three criteria: a BMI over 35, at least 100 lbs. overweight, or 100% above ideal body weight; and a person is super-obese if he weighs in excess of 350 lbs.
It is well recognized that being overweight or obese raises many significant health implications. For example, obesity increases the risk of many diseases and health conditions, including: hypertension, dyslipidemia (for example, high total cholesterol or high levels of triglycerides), type 2 diabetes, coronary heart disease, stroke, gallbladder disease, osteoarthritis, sleep apnea, and respiratory problems. In addition to the health implications, overweight and obesity have a significant economic impact on the U.S. health care system. Medical costs associated with overweight and obesity may involve direct and indirect costs. Direct medical costs may include preventive, diagnostic, and treatment services related to obesity. Indirect costs relate to morbidity and mortality costs, where morbidity costs are defined as the value of income lost from decreased productivity, restricted activity, absenteeism, and bed days, and mortality costs are the value of future income lost by premature death. According to a study of national costs attributed to both overweight (BMI 25-29.9) and obesity (BMI greater than 30), medical expenses accounted for 9.1 percent of total U.S. medical expenditures in 1998 and may have reached as high as $78.5 billion ($92.6 billion in 2002 dollars). Approximately half of these costs were paid by Medicaid and Medicare. A more recent study focused on state-level estimates of the total obesity attributable direct medical expenditures. State-level estimates range from $87 million (Wyoming) to $7.7 billion (California). Obesity-attributable Medicare estimates range from $15 million (Wyoming) to $1.7 billion (California), and obesity-attributable Medicaid expenditures range from $23 million (Wyoming) to $3.5 billion (New York). The state differences in obesity-attributable expenditures are partly driven by the differences in the size of each state's population.
According to the CDC, overweight and obesity are a result of energy imbalance over a long period of time due to a combination of several factors. These factors include, individual behaviors, environmental factors, and genetics. Energy imbalance results when the number of calories consumed is not equal to the number of calories used. When the quantity of calories consumed is greater than calories used, weight gain results. In the United States and many other highly developed countries, the growing prevalence of pre-packaged foods, fast food restaurants, and soft drinks, that tend to be high in fat, sugar, and calories, increase a person's calorie consumption. In addition, portion size has also increased which causes people to eat more during a meal or snack, thereby increasing their calorie consumption. If the body does not burn off the extra calories consumed from larger portions, fast food, or soft drinks, weight gain will likely occur. Despite the well-known benefits of being physically active, most Americans lead a sedentary life style. According to the Behavioral Risk Factor Surveillance System, in 2000 more than 26% of adults reported limited or no physical activity during the course of an average week. Regarding the environmental factor, people may make decisions based on their environment or community. For example, a person may choose not to walk to the store or to work because of a lack of sidewalks. Genetics have been proven to play a role in obesity. For example, genes can directly cause obesity in disorders such as Bardet-Biedl syndrome and Prader-Willi syndrome. However, genes do not always predict future health; in some cases multiple genes may increase one's susceptibility for obesity and require outside factors, such as abundant food supply or little physical activity.
Conventional approaches to combat overweight and obesity have led doctors to surgically modify patients' anatomies in an attempt to reduce consumption by inducing satiety or a “full” feeling in the patient, thereby reducing the desire to eat. Examples include stomach stapling, or gastroplasties, to reduce the volumetric size of the stomach. In addition, two procedures, the Roux-en-Y gastric bypass and the biliopancreatic diversion with duodenal switch (BPD), reduce the size of the stomach and the effective-length of intestine available for nutrient absorption. These two procedures reduce the stomach volume and the ability of a patient to consume food. In an attempt to limit nutrient absorption in the digestive tract, at least one company has introduced a sleeve that is implanted in obese patients. U.S. Pat. No. 7,025,791 discloses a bariatric sleeve that is anchored in the stomach and extends through the pylorus and duodenum and beyond the ligament of Treitz. All chyme exiting the stomach is funneled through the sleeve and bypasses the duodenum and proximal jejunum. By directing the chyme through the sleeve, the digestion and absorption process in the duodenum is interrupted because the chyme cannot mix with the fluids in the duodenum. Because there is no mixing of bile with the chyme until the jejunum, the absorption of fats and carbohydrates is reduced. Although these conventional methods and approaches have had some success, they suffer from a number of limitations including high correction and mortality rates. Also, conventional methods are costly and prone to adaptation by the patient's digestive tract which reduces the effectiveness of the method.
Accordingly there is a need for an implantable weight loss device that is effective in prompting satiety while being minimally invasive and not irritable to patients over time. At the same time, there is a need to provide a weight control device that can be implanted with an endoscope during a visit to a doctor's office, and that does not require a hospital visit. Finally, it would be advantageous to provide treatment methods for combating overweight or obesity based upon the weight loss device that forms a gastric outlet obstruction in the stomach to prompt satiety and reduce food consumption.